Typically, agricultural trailer designs need to be easily configured to meet customer requests. One of these configuration is axle configuration between single and multiple axles. The base design or main structure need to accept different axle configurations. When considering single and tandem/walking axle design the challenge become the design of the multiple axle structure. A most common method of a trailer to accept multiple axles is to use the trailer main frame structure as part of the support structure for the multiple axles. This means multiple main frame configurations for various axle configuration.
A characteristic of multiple axles when turning is significant tire side loading, this load is transmitted into the axle and main structures. These designs have multiple pivot points to resist the side loading force. These pivots are commonly greased and are under the main trailer frame.